X-ray computed tomography apparatuses provided with a high-voltage X-ray device capable of altering CT imaging parameters such as a tube voltage are already known. For such X-ray computed tomography apparatuses, it is necessary to acquire correction data for calibration, etc., for respective tube voltage values. The correction data for a tube voltage value is acquired during a rotation of an X-ray tube and an X-ray detector. Accordingly, the time required for acquiring correction data increases as the number of types or levels of variable CT imaging parameters increases.